package textProcessing;

/*

Porter stemmer in Java. The original paper is in

    Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
    no. 3, pp 130-137,

See also http://www.tartarus.org/~martin/PorterStemmer

History:

Release 1

Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
is then out outside the bounds of b.

Release 2

Similarly,

Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
b[j] is then outside the bounds of b.

Release 3

Considerably revised 4/9/00 in the light of many helpful suggestions
from Brian Goetz of Quiotix Corporation (brian@quiotix.com).

Release 4

*/

import java.io.*;

/**
* Stemmer, implementing the Porter Stemming Algorithm
*
* The Stemmer class transforms a word into its root form.  The input
* word can be provided a character at time (by calling add()), or at once
* by calling one of the various stem(something) methods.
*/

class Porter
{
    private char[] b;
	private int i,     /* offset into b */
	 			i_end, /* offset to end of stemmed word */
	 			j, k;
    private static final int INC = 50;
                  /* unit of size whereby b is increased */
    public Porter()
    {
		b = new char[INC];
		i = 0;
		i_end = 0;
	}

	/**
	 * Add a character to the word being stemmed.  When you are finished
	 * adding characters, you can call stem(void) to stem the word.
	 */

    public void add(char ch)
	{
        if (i == b.length)
        {
            char[] new_b = new char[i+INC];
			for (int c = 0; c < i; c++) new_b[c] = b[c];
			b = new_b;
        }
        b[i++] = ch;
    }


	/** 
	 * Adds wLen characters to the word being stemmed contained in a portion
	 * of a char[] array. This is like repeated calls of add(char ch), but
	 * faster.
	 */

    public void add(char[] w, int wLen)
    {
        if (i+wLen >= b.length)
		{
            char[] new_b = new char[i+wLen+INC];
            for (int c = 0; c < i; c++) new_b[c] = b[c];
            b = new_b;
        }
        for (int c = 0; c < wLen; c++) b[i++] = w[c];
    }

	/**
	 * After a word has been stemmed, it can be retrieved by toString(),
	 * or a reference to the internal buffer can be retrieved by getResultBuffer
	 * and getResultLength (which is generally more efficient.)
	 */
	public String toString() 
	{ 
		return new String(b,0,i_end); 
	}

	/**
	 * Returns the length of the word resulting from the stemming process.
	 */
	public int getResultLength() 
	{ 
		return i_end; 
	}

	/**
	 * Returns a reference to a character buffer containing the results of
	 * the stemming process.  You also need to consult getResultLength()
	 * to determine the length of the result.
	 */
	public char[] getResultBuffer() 
	{ 
		return b; 
	}

	/* cons(i) is true <=> b[i] is a consonant. */

    private final boolean cons(int i)
    {
        switch (b[i])
        {
            case 'a': case 'e': case 'i': case 'o': case 'u': return false;
            case 'y': return (i==0) ? true : !cons(i-1);
            default: return true;
        }
    }

/* m() measures the number of consonant sequences between 0 and j. if c is
   a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
   presence,

      <c><v>       gives 0
      <c>vc<v>     gives 1
      <c>vcvc<v>   gives 2
      <c>vcvcvc<v> gives 3
      ....
*/

    private final int m()
    {
        int n = 0;
        int i = 0;
        while(true)
        {
            if (i > j)
                return n;
            if (! cons(i))
                break;
			
            i++;
        }
        i++;

        while(true)
        {
            while(true)
            {
                if (i > j)
                    return n;
                if (cons(i))
                    break;
                i++;
            }
            i++;
			n++;

            while(true)
            {
                if (i > j)
                    return n;
                if (! cons(i))
                    break;
                i++;
            }
            i++;
        }
    }

	/* vowelinstem() is true <=> 0,...j contains a vowel */
	
	private final boolean vowelinstem()
	{ 
		int i; 
		for (i = 0; i <= j; i++) 
			if (! cons(i)) 
                return true;
        return false;
	}

	/* doublec(j) is true <=> j,(j-1) contain a double consonant. */

	private final boolean doublec(int j)
	{  
		if (j < 1) 
			return false;
		if (b[j] != b[j-1])
			return false;
		return cons(j);
	}

/* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
   and also if the second c is not w,x or y. this is used when trying to
   restore an e at the end of a short word. e.g.

      cav(e), lov(e), hop(e), crim(e), but
      snow, box, tray.

*/

	private final boolean cvc(int i)
	{  
        if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2)) return false;
        {
			int ch = b[i];

            if (ch == 'w' || ch == 'x' || ch == 'y')
                return false;
        }
		return true;
    }

	private final boolean ends(String s)
	{  
		int l = s.length();
		int o = k-l+1;

		if (o < 0) 
			return false;

		for (int i = 0; i < l; i++) 
			if (b[o+i] != s.charAt(i)) 
				return false;

		j = k-l;
		return true;
    }

/* setto(s) sets (j+1),...k to the characters in the string s, readjusting
   k. */

	private final void setto(String s)
	{  
		int l = s.length();
		int o = j+1;

		for (int i = 0; i < l; i++) 
			b[o+i] = s.charAt(i);

		k = j+l;
	}

/* r(s) is used further down. */

	private final void r(String s) 
	{ 
		if (m() > 0) 
			setto(s); 
	}

/* step1() gets rid of plurals and -ed or -ing. e.g.

       caresses  ->  caress
       ponies    ->  poni
       ties      ->  ti
       caress    ->  caress
       cats      ->  cat

       feed      ->  feed
       agreed    ->  agree
       disabled  ->  disable

       matting   ->  mat
       mating    ->  mate
       meeting   ->  meet
       milling   ->  mill
       messing   ->  mess

       meetings  ->  meet

*/

private final void step1()
{  if (b[k] == 's')
   {
       if (ends("sses")) k -= 2; else
           if (ends("ies")) setto("i"); else
               if (b[k-1] != 's') k--;
   }

   if (ends("eed")) { 
       if (m() > 0) k--;
   }
   else
       if ((ends("ed") || ends("ing")) && vowelinstem())
       {
           k = j;
           if (ends("at")) setto("ate");
           else if (ends("bl")) setto("ble");
               else if (ends("iz")) setto("ize");
               else if (doublec(k))
               {
                   k--;
                   {
                       int ch = b[k];
                       if (ch == 'l' || ch == 's' || ch == 'z')
                           k++;
                   }
               }
               else if (m() == 1 && cvc(k))
                   setto("e");
       }
}

/* step2() turns terminal y to i when there is another vowel in the stem. */

private final void step2()
{
    if (ends("y") && vowelinstem())
        b[k] = 'i';
}

/* step3() maps double suffices to single ones. so -ization ( = -ize plus
   -ation) maps to -ize etc. note that the string before the suffix must give
   m() > 0. */

private final void step3() { if (k == 0) return; /* For Bug 1 */ switch (b[k-1])
{
    case 'a': if (ends("ational")) { r("ate"); break; }
              if (ends("tional")) { r("tion"); break; }
              break;

    case 'c': if (ends("enci")) { r("ence"); break; }
              if (ends("anci")) { r("ance"); break; }
              break;

    case 'e': if (ends("izer")) { r("ize"); break; }
              break;

    case 'l': if (ends("bli")) { r("ble"); break; }
              if (ends("alli")) { r("al"); break; }
              if (ends("entli")) { r("ent"); break; }
              if (ends("eli")) { r("e"); break; }
              if (ends("ousli")) { r("ous"); break; }
              break;

    case 'o': if (ends("ization")) { r("ize"); break; }
              if (ends("ation")) { r("ate"); break; }
              if (ends("ator")) { r("ate"); break; }
              break;

    case 's': if (ends("alism")) { r("al"); break; }
              if (ends("iveness")) { r("ive"); break; }
              if (ends("fulness")) { r("ful"); break; }
              if (ends("ousness")) { r("ous"); break; }
              break;

    case 't': if (ends("aliti")) { r("al"); break; }
              if (ends("iviti")) { r("ive"); break; }
              if (ends("biliti")) { r("ble"); break; }
              break;

    case 'g': if (ends("logi")) { r("log"); break; }
} }

/* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */

private final void step4() { switch (b[k])
{
    case 'e': if (ends("icate")) { r("ic"); break; }
              if (ends("ative")) { r(""); break; }
              if (ends("alize")) { r("al"); break; }
              break;

    case 'i': if (ends("iciti")) { r("ic"); break; }
              break;

    case 'l': if (ends("ical")) { r("ic"); break; }
              if (ends("ful")) { r(""); break; }
              break;

    case 's': if (ends("ness")) { r(""); break; }
              break;
} }

/* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */

private final void step5()
{   if (k == 0) return; /* for Bug 1 */ switch (b[k-1])
    {  case 'a': if (ends("al")) break; return;

       case 'c': if (ends("ance")) break;
                 if (ends("ence")) break; return;

       case 'e': if (ends("er")) break; return;

       case 'i': if (ends("ic")) break; return;

       case 'l': if (ends("able")) break;
                 if (ends("ible")) break; return;

       case 'n': if (ends("ant")) break;
                 if (ends("ement")) break;
                 if (ends("ment")) break;
                 /* element etc. not stripped before the m */
                 if (ends("ent")) break; return;

       case 'o': if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
                                 /* j >= 0 fixes Bug 2 */
                 if (ends("ou")) break; return;
                 /* takes care of -ous */

       case 's': if (ends("ism")) break; return;

       case 't': if (ends("ate")) break;
                 if (ends("iti")) break; return;

       case 'u': if (ends("ous")) break; return;

       case 'v': if (ends("ive")) break; return;

       case 'z': if (ends("ize")) break; return;

       default: return;
    }
    if (m() > 1) k = j;
}

/* step6() removes a final -e if m() > 1. */

private final void step6()
{  
    j = k;
    if (b[k] == 'e')
    {
        int a = m();
        if (a > 1 || a == 1 && !cvc(k-1))
            k--;
    }
    if (b[k] == 'l' && doublec(k) && m() > 1)
        k--;
}

/** Stem the word placed into the Stemmer buffer through calls to add().
 * Returns true if the stemming process resulted in a word different
 * from the input.  You can retrieve the result with
 * getResultLength()/getResultBuffer() or toString().
 */
public void stem()
{  
    k = i - 1;
    if (k > 1)
    {
        step1();
        step2();
        step3();
        step4();
        step5();
        step6();
    }

   i_end = k+1;
   i = 0;
}

/** Test program for demonstrating the Stemmer.  It reads text from a
 * a list of files, stems each word, and writes the result to standard
 * output. Note that the word stemmed is expected to be in lower case:
 * forcing lower case must be done outside the Stemmer class.
 * Usage: Stemmer file-name file-name ...
 */
public static void main(String[] args)
{
   char[] w = new char[501];
   Porter s = new Porter();
   for (int i = 0; i < args.length; i++)
   try
   {
       FileInputStream in = new FileInputStream(args[i]);

       try
       {
           while(true)
           {
               int ch = in.read();
               if (Character.isLetter((char) ch))
               {
                   int j = 0;
                   while(true)
                   {
                       ch = Character.toLowerCase((char) ch);
                       w[j] = (char) ch;
                       if (j < 500) j++;
                       ch = in.read();
                       if (!Character.isLetter((char) ch))
                       {
                           /* to test add(char ch) */
                           for (int c = 0; c < j; c++)
                               s.add(w[c]);

                           /* or, to test add(char[] w, int j) */
                           /* s.add(w, j); */

                           s.stem();
                           {
                               String u;

                               /* and now, to test toString() : */
                               u = s.toString();

                               /* to test getResultBuffer(), getResultLength() : */
                               /* u = new String(s.getResultBuffer(), 0, s.getResultLength()); */

                               System.out.print(u);
                           }
                           break;
                       }
                   }
               }
               if (ch < 0)
                   break;

               System.out.print((char)ch);
           }
       }
       catch (IOException e)
       {
           System.out.println("error reading " + args[i]);
           break;
       }
   }
   catch (FileNotFoundException e)
   {  
       System.out.println("file " + args[i] + " not found");
       break;
   }
}
}
